The primary purpose of Clinical Core A is to provide access to patients with ANCA-associated small vessel vasculitis (SW) in order to obtain biological samples in conjunction with clinical information for the use in three of the proposed projects of this program project. Access to this patient population and to patients at different disease stages is critical for the successful completion of these projects. Clinical stages of particular interest in this patient population include: remission, remission on therapy, treatment resistance, relapse and end stage renal disease. The Core will also be responsible for processing and storing biologic samples, as well as managing the database with respect to consent forms, labeling and storage locations of specimens, and clinical assessment of disease stages and outcomes. The Core will also provide the study design and statistical expertise needed to publish and present abstracts and manuscripts. The faculty and staff who comprise the Core have a long term commitment to research in this arena and have well documented track record of publishing abstracts and manuscripts with the principal and co-investigators, with a particular focus in the area of vasculitis.